Customizing the spent coffee for Trichoderma reesei cellulase immobilization by modification with activating agents.

This study has explored the possibility to reuse the waste, spent coffee material for the cellulase enzyme immobilization. By the coffee surface modification with different activating agents, it was attempted to develop the convenient method for creation of a capable porous carrier for this purpose. Among the most common activating agents, glutaraldehyde, chlorine dioxide and hydrogen peroxide provided the most acceptable choice for the coffee surface modification. The changes that occurred on the coffee surface due to agents' treatment exposure were recorded by using of the FTIR spectra and SEM micrographs. The highest immobilization yield (55%) and immobilization efficiency (45%) were attained during 30min of the treatment time, by employing of 30% chlorine dioxide aqueous solution within 6mL/g activator/carrier ratio. The kinetic process was found to be predicted by the pseudo-second-order model. The cellulase immobilization onto the coffee surface provides an excellent base for increasing the enzyme availability to the substrate and enhancing the enzyme productivity, by offering the new perspectives to the industrial sector.

Utilization of spent coffee grounds for isolation and stabilization of Paenibacillus chitinolyticus CKS1 cellulase by immobilization.

This study has explored the feasibility of using spent coffee grounds as a good supporting material for the Paenibacillus chitinolyticus CKS1 cellulase immobilization. An optimal operational conditions in a batch-adsorption system were found to be: carrier mass of 12 g/L, under the temperature of 45 °C and no pH adjustments. The immobilization yield reached about 71%. An equilibrium establishment between the cellulase and the carrier surface occurred within 45 min, whereas the process kinetics may be predicted by the pseudo-second-order model. An immobilized cellulase preparation expressed very good avicelase activity, this reached up to 2.67 U/g, and revealed an improved storage stability property, compared to free enzyme sample counterpart. The addition of metal ions, such as K(+) and Mg(2+) did not affect positively immobilization yield results, but on the contrary, contributed to an improved bio-activities of the immobilized cellulase, thus may be employed before each enzyme application. The method developed in this study offers a cheap and effective alternative for immediate enzyme isolation from the production medium and its stabilization, compared to other carriers used for the immobilization.

Stability of the pyrethroid pesticide bifenthrin in milled wheat during thermal processing, yeast and lactic acid fermentation, and storage.

BACKGROUND: Pesticide residues have become an unavoidable part of food commodities. In the context of increased interest for food processing techniques as a tool for reducing pesticide residues, it is interesting to study the potential loss of pesticides during lactic acid and yeast fermentation. In the present paper the effect of fermentation by Lactobacillus plantarum and Saccharomyces cerevisiae and storage on 23 °C on bifenthrin in wheat was investigated. In addition, the effect of sterilisation (applied in order to avoid contamination with wild microorganism strains, i.e. to determine the individual effects of used strains) on bifenthrin degradation was tested as well. RESULTS: No significant loss of bifenthrin was observed during storage, or after the sterilisation. During the lactic acid fermentation, reduction within wheat fortified with 0.5 mg kg(-1) was 42%, while quite lower within samples fortified with 2.5 mg kg(-1) , maximum 18%. In contrast, bifenthrin concentration was not reduced during yeast fermentation, as the reduction in fortified samples was in the range of spontaneous chemical degradation during incubation period. CONCLUSION: Possible bifenthrin contamination in wheat, in amounts over the maximum residue limits, could not be reduced by sterilisation or by yeast fermentation, but lactic acid fermentation could be an effective tool for minimising residual contamination.